320 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



be made into a new genus, bearing the same relation to Sidonops 

 as Caminella does to I sops. Possibly some of the more recent species 

 fall in this group. In S. oxyastra Lendenfeld (1910, p. 40) for 

 instance, Lendenf eld's figure (pi. 7, fig. 2) suggests that perhaps the 

 uniporal excurrent canals are not chone-canals. 



The typical chones, incurrent and excurrent, are beautifully illus- 

 trated in S. oicolor Lendenfeld (1910, p. 48, pi. 9, figs. 15, 16). 

 In some other species, S. oxyastra Lendenfeld (1910, p. 41), S. 

 angulata Lendenfeld (1910, p. 26), the afferent cortical canals are 

 differentiated into well-marked subdermal spaces and endochonal 

 canals as in Geodia stellata Lendenfeld, etc. 



Since Lendenf eld's Tetraxonia (1903) species of Sidonops have 

 been described by Lendenfeld, 1910 (pp. 18, 24, 40, 46) ; Hentschel, 

 1912 (p. 315) ; Stephens, 19156 (p. 18). 



SIDONOPS MICROSPINOSA, new species. 



Plate 38, fig. 2 ; plate 46, figs. 6, 9, 10 ; plate 47, figs. 1, 2, 3, 8. 



A specimen from Station D5593. Sponge vase-shaped, tapering 

 below to an attached base; cavity of the vase occupies the whole of 

 the upper surface and is very shallow. Sponge 90 mm. high, 75 mm. 

 wide above, 45 mm. wide at the base; cloacal cavity about 15 mm. 

 deep. 



Sponge is brown, dense, and heavy; the cortex somewhat lighter 

 in color than the interior. All canals are small. Both outer and 

 cloacal surfaces are smooth, without projecting spicules: outer sur- 

 face somewhat uneven. 



The outer surface of the sponge is closely dotted with pore areas 

 (pi. 46, figs. 6, 9; pi. 47, fig. 1), 180-360 \i in diameter and about 0.25 

 mm. apart. These areas which are rounded and plainly visible to the 

 eye, are cortical areas without sterrasters but with abundant dermal 

 spherasters. A pore area may include as many as six pores, but very 

 often the number is only two or three, and frequently the area has 

 only a single pore. The open pores measure up to 70 [x in diameter. 

 Many, however, are much smaller, doubtless nearly closed, and in 

 many areas the pores are completely closed. From the pores of an 

 area pore canals (pi. 46, fig. 9, p. c), in general oblique, pass into a 

 radial afferent chone canal (r. a. c). The inner end of the chone 

 (ch. e.) projects into a subcortical crypt (s. c). Round the open 

 pores the spherasters are densely grouped, and they also line the 

 pore canals. When the pore or pore canal is closed, its position is 

 marked by a dense group or a streak, respectively, of spherasters. 

 The radial chone-canal is lined with oxyasters. 



The small number of pores in many areas and the fact that some 

 areas have but one pore, make it clear that this sponge closely ap- 



